Are Probiotics Bad For You?

Written by Dr. Steve Chaney on . Posted in Probiotics

Are Probiotics Worthless?

Author: Dr. Stephen Chaney

 

are probiotics bad for youProbiotics (friendly gut bacteria) are all the rage. There is big money to be made, so the internet is ablaze with all the amazing things probiotics can do for you. Of course, most of those articles are posted by companies wanting to sell you their miracle mixture of probiotic bacteria.

In the last few weeks, you may have seen headlines proclaiming that probiotics are worthless. You just poop them out. Even worse, they may be upsetting the natural balance of bacteria in your gut. Are probiotics bad for you?  They may be.

As usual, the truth is somewhere in the middle. Before I start sorting out fact from fiction, let me remind you of some important facts about gut bacteria that I covered in a recent article of “Health Tips From The Professor”:

  • The composition of bacteria in our gut is influenced by what we eat. For example, meat eaters have a completely different composition of gut bacteria than vegetarians.
  • Fiber from whole plant foods is a major food source for healthy gut bacteria.
  • Each plant-based food group and each food within that group has a unique blend of fibers. We should probably aim for a wide variety of whole plant foods in our diet.

Are Probiotics Worthless?

 

are probiotics bad for you studyLet’s start with the study (N. Zmora et al, Cell 174, 1388-1405, 2018 ) that generated the headlines proclaiming that probiotics were worthless.

The characteristics of the study with my comments are as follows:

  • The study had 15 subjects who were given either a commercially available probiotic supplement or a placebo containing cellulose. It was a very small study.
  • The probiotic supplement contained 25 billion colony forming units of 11 commonly used strains of bacteria. Its manufacturer claimed the bacteria survived stomach acid and colonized the intestine, but no references were given for published clinical studies backing up that claim. It is buyer beware in the supplement industry. I would not believe any claims about a probiotic supplement that were not backed up by published clinical studies.
  • The investigators measured bacterial colonization of the mucosal cells lining the intestine rather than the population of bacteria that ended up in the feces. This is the “gold standard” for measuring colonization of the intestine by probiotic bacteria. However, it requires a colonoscopy before the study started and a second colonoscopy 3 weeks later. As any of you who have had a colonoscopy can attest, this is a very invasive procedure. It probably accounts for the small size of the study. In fact, the study started with 28 subjects and 13 dropped out, one after suffering a serious adverse reaction to the first colonoscopy. My point is simply that I don’t expect to see a lot of this type of study.

are probiotics bad for you supplementsThe results of the study with my comments are as follows:

  • Overall, the particular probiotic supplement used in this study didn’t work very well. There was minimal colonization of the intestinal mucosal cells by the bacteria in the probiotic supplement. Some did better than others, but the net colonization was small. We don’t know whether the results would have been the same with other probiotic supplements, but this is the finding that generated all the headlines. However, it is the rest of the study that is interesting.
  • The probiotic supplement worked better for some subjects than for others. Some of the subjects in the study were “permissive.” The probiotic cells colonized their intestinal mucosal cells with high efficiency. Other subjects were “resistant.”  Probiotic bacteria had a great deal of difficulty colonizing their intestinal mucosal cells. This doesn’t surprise me. Most clinical studies report an average result. They don’t report individual variations. This is one of the first studies to report on individual variation of probiotic colonization. As such, it has important implications. It means that even though you may be taking a probiotic supplement that has been “clinically proven” to survive stomach acid and colonize the intestine, it may not work well for you. But, wait, the study gets even more interesting.
  • How well the probiotic supplement worked depended on the population of bacteria in the intestine to begin with. “Permissive” and “resistant” subjects had very different species of bacteria in their intestine at the beginning of the trial. There was a characteristic grouping of bacteria in “permissive” subjects and a different characteristic grouping of bacteria in “resistant” subjects. This is the part of the study that should have generated headlines. Let’s put this part of the study into perspective.

We each have around 38 trillion bacteria in our intestines. Let’s assume that all 25 billion bacteria in the probiotic supplement make it into the intestine intact. You have just dropped them into hostile territory where they are outnumbered 1,000 to 1. We know that some bacteria secret substances that support the growth of “like-minded” bacteria. That’s why certain species of bacteria tend to cluster together. We also know that bacteria secret toxins, so they can out-compete bacteria they don’t like. So, it is no wonder the survival of the probiotic bacteria depends on which species of bacteria are already populating the intestine when they arrive on the scene.

This study leaves a lot of unanswered questions:

  • What determined the original population of gut bacteria? Was it the genetics or health of the subject? Or, was it the food they were eating? We simply don’t know.
  • We were sending these probiotic bacteria into hostile territory. Were we giving them the food they needed to survive? Would the results have been different for the “resistant” subjects if they had been eating a different kind of fiber-rich foods, or taken a prebiotic supplement? Again, we just don’t know.

If we want to optimize the results of probiotic supplementation, these are the questions we should be asking.

 

Are Probiotics Bad For You?

are probiotics bad for you thumbs downNow, let’s turn to the study (J. Suez et al, Cell 174, 1406-1423, 2018) generating the headlines saying that probiotic supplements may be bad for you. This study was looking specifically at the use of probiotics following antibiotic use.

The study reported when probiotics are used following antibiotic use, they delay, rather than enhance, the recovery of intestinal bacteria back to the same number and type of bacteria that existed prior antibiotic use. That’s the finding that generated all the headlines. Let’s put that into perspective.

Both the headlines and interpretation of the data were inaccurate.

  • Probiotics actually had a relatively small effect on the ability to regain your “normal” population of intestinal bacteria. The headlines made it sound as if the delay was significant and that you never regained your “normal” population of intestinal bacteria. In fact by one measure, the population of intestinal bacteria was 70% normal by 5 days, 80% normal by 20 days, and 95% normal by 90 days.
  • Poop pills work better but will probably never be popular. When the investigators extracted intestinal bacteria from the subject’s poop and put them into pills prior to the study, the poop pills restored the “normal” population of intestinal bacteria much more quickly. However, I doubt that poop pills will become popular any time soon.
  • Your “normal” population of intestinal bacteria may not be the optimal population of intestinal bacteria. The headlines implied that the fact you never recovered your “normal” population of intestinal bacteria was a bad thing. That assertion assumes that all of us have the optimal population of intestinal bacteria to begin with, an assertion that almost any expert in the field would find absurd. The last time I checked, one of the major reasons for taking probiotic supplements was to change our population of intestinal bacteria for the better.

The study ignores the major reasons for taking a probiotic supplement after antibiotic use. Most people are not taking the probiotic supplement to restore their original population of intestinal bacteria. They are taking it to:

  • Prevent “bad guys” like yeast from filling the void caused by the antibiotics.
  • Improve digestion. Some strains of intestinal bacteria play an important role in digestion. Because antibiotics wipe out those bacteria, they often cause gas, diarrhea, and bloating. After antibiotic use, people are taking probiotic bacteria with digestive benefits to eliminate those digestive issues as quickly as possible.
  • Strengthen the immune system. People are generally taking antibiotics to fight some sort of infection. Some strains of intestinal bacteria play an important role in immunity. Because antibiotics wipe out those bacteria, they weaken the immune system. After antibiotic use, people are taking probiotics to strengthen the immune system as quickly as possible

In short, taking probiotic supplements that are proven to improve digestion and strengthen the immune system play an important role in minimizing the side effects of antibiotic use.

What Does This Mean For You?

are probiotics bad for you truthAt the beginning of this article I said; “The truth lies somewhere in between.” The first study is a perfect example.

  • It was valuable in that it challenged the assertion by some manufacturers that their probiotics survive stomach acid and work equally well for everyone. At the very least, it suggests that we should demand clinical proof that any probiotic supplement colonizes the intestine and provides a health benefit before we use it.
  • The most interesting finding from the first study is that probiotics work much better for some people than for others, and how well they work depends on the population of bacteria in our gut prior to taking the antibiotic. We have much more to learn about this individual variability, and how to control it.

Until we know more, my best advice is to eat a fiber-rich, primarily plant-based diet with as many different varieties of fruits, vegetables, whole grains, and legumes as possible. Providing a variety of fibers is important because at least some of them will likely support the growth of the bacteria in the probiotic supplement. Prebiotics may be of some help, but only if they have been shown to be effective for the particular strains of probiotic bacteria they are paired with.

The second study was much less enlightening. It reported that taking a probiotic after antibiotic use slowed the return to the original population of intestinal bacteria. My response to that is: “So what?”

  • The effect was minimal.
  • The purpose of probiotics is to improve on the population of intestinal bacteria, not to return to the same population of bacteria you had prior to antibiotic use.
  • Probiotics are taken after antibiotic use for reasons that have nothing to do with restoring the original population of intestinal bacteria.

 

The Bottom Line

 

Two recent studies have challenged the benefits of probiotic use.

The first study provided some valuable insights.

  • It reported that a particular probiotic supplement did a very poor job of colonizing the intestine. We have no idea whether that would apply to other probiotic supplements, but that was the result that generated all the headlines. At the very least, it suggests that we should demand clinical proof that any probiotic supplement colonizes the intestine and provides a health benefit before we use it.
  • However, the most interesting finding from the first study is that probiotics work much better for some people than for others, and how well they work depends on the population of bacteria in our gut prior to taking the antibiotic. We have much more to learn about this individual variability, and how to control it.

The second study was much less enlightening. It reported that taking a probiotic after antibiotic use slowed the return to the “normal” population of intestinal bacteria that were present before antibiotic use. My response to that is: “So what?”

  • The purpose of probiotics is to improve on the population of intestinal bacteria, not to return to the same population of intestinal bacteria you had prior to taking an antibiotic.
  • Probiotics are taken after antibiotic use for reasons that have nothing to do with restoring the original population of intestinal bacteria.

For more details, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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The Truth About Vitamin D

Posted December 11, 2018 by Dr. Steve Chaney

Does Vitamin D Reduce Risk Of Heart Disease & Cancer?

Author: Dr. Stephen Chaney

 

the truth about vitamin dYou have every right to be confused. One day you are told that vitamin D reduces your risk of heart disease and cancer. The next day you are told vitamin D makes has no effect on those diseases. You are told vitamin D is a waste of money. What should you believe?  What is the truth about vitamin D?

In mid-November a major clinical study called VITAL was published. It examined the effect of vitamin D and omega-3s on heart disease and cancer risk. Last week I wrote about the omega-3 portion of the study. This week I will cover the vitamin D portion of the study.

Once again, if you rely on the media for your information on supplementation, you are probably confused. Headlines ranged from “Vitamin D Is Ineffective For Preventing Cancer And Heart Disease to “Vitamin D Lowers Odds Of Cancer Death.” What is the truth?

The problem is that reporters aren’t scientists. They don’t know how to interpret clinical studies. What they report is filtered through their personal biases. That is why I take the time to carefully evaluate the clinical studies, so I can provide you with accurate information. Let me sort through the dueling headlines and give you the truth about vitamin D, cancer, and heart disease.

How Was The Study Designed?

the truth about vitamin d studyThe VITAL study (JE Manson et al, New England Journal of Medicine, DOI: 10.1056/NEJMoa1811403) enrolled 25,871 healthy adults (average age = 67) in the United States. The study participants were 50% female, 50% male, and 20% African American. None of the participants had preexisting cancer or heart disease. The characteristics of the study group were typical of the American population at that age, namely:

  • The average BMI was 28, which means that most of the participants were significantly overweight.
  • 7% of them had diabetes.

Study participants were given questionnaires on enrollment to assess clinical and lifestyle factors including dietary intake. Blood samples were taken from about 65% of the participants to determine 25-hydroxyvitamin D levels (a measure of vitamin D status) at baseline and at the end of the first year. The participants were given either 2,000 IU of vitamin D/day or a placebo and followed for an average of 5.3 years.

There were two important characteristics of the participants in this study that may have influenced the outcome.

  • The average 25-hydroxyvitamin D level of participants at the beginning of the study was 31 ng/ml (78 nmol/L). The NIH considers 20-50 ng/ml (50-125 nmol/L) to be the optimal level of 25-hydroxyvitamin D for most physiological functions. This means that study participants started in the middle of the optimal range with respect to vitamin D status.

[Note: The NIH defines the 20-50 ng/ml range as “adequate.”  However, I know many of my readers like to aim beyond adequate to reach what they consider to be “optimal.”  In the case of vitamin D, that might not be a good idea. The NIH considers anything above 50 ng/ml as associated “with potentially adverse effects.”  For that reason, I will refer to the 20-50 ng/ml range as optimal for this article. I wouldn’t want to encourage my readers to be aiming for above 50 ng/ml.]

  • Only 12.7% of participants had 25-hydroxyvitamin D levels below 20 ng/ml, which the NIH considers to be inadequate. The results with this group were not statistically different from the study participants with optimal vitamin D status, but it is not clear that there were enough people in this subgroup for a statistically valid comparison with participants starting with an optimal vitamin D status.
  • At the end of the first year, 25-hydroxyvitamin D levels in the treatment group increased to 42 ng/ml (105 nmol/L), which is near the upper end of the optimal range. Thus, for most of the participants, the study was evaluating whether there was a benefit of increasing vitamin D status from the middle to the upper end of the optimal range.
  • The study allowed subjects to continue taking supplements that contained up to 800 IU of vitamin D. While the authors tried to correct for this statistically, it is a confounding variable.

Does Vitamin D Reduce The Risk Of Cancer?

 

the truth about vitamin d and cancerYou may remember from last week that omega-3s were more effective for reducing heart disease risk than for reducing cancer risk. What is the truth about vitamin D and cancer risk?   The results are reversed for vitamin D, so I will discuss cancer first.

The study reported that vitamin D supplementation did not reduce a diagnosis of invasive cancer of any type, breast cancer, prostate cancer, or colon cancer during the 5.3-year time-period of this study. This was the result that was reported in the abstract and was what lazy journalists, who never read past the abstract, reported.

However, the rest of the study was more positive. For example, occurrence of invasive cancer of any type was reduced by:

  • 23% in African-Americans.
  • 24% in patients with a healthy body weight.

Several previous studies have suggested that vitamin D may be more effective at preventing cancer in people with a healthy body weight, but the mechanism of this effect is currently unknown.

Most previous studies have not included enough African-Americans to determine whether they respond more favorably to vitamin D supplementation. However, African-Americans have a higher risk of cancer, so this finding deserves follow-up.

In addition, when the study looked at deaths from cancer, the results were very positive. For example:

  • Cancer deaths during the 5.3-year study period were reduced by 17%.
  • The longer vitamin D supplementation was continued the more effective it became at reducing cancer deaths. For example,
  • When the authors excluded cancer deaths occurring during the first year of supplementation, vitamin D reduced cancer deaths by 21%.
  • When the authors excluded cancer deaths occurring during the first two years of supplementation, vitamin D reduced cancer deaths by 25%.

Finally, no side effects were noted in the vitamin D group.

 

Does Vitamin D Reduce The Risk Of Heart Disease?

 

the truth about vitamin d and heart diseaseThe VITAL study also looked at the effect of vitamin D on heart disease risk. What is the truth about vitamin D and heart disease?  The results from this study were uniformly negative. There was no effect of vitamin D supplementation on all major cardiovascular events combined, heart attack, stroke, or death from heart disease. Does that mean vitamin D has no role in reducing heart disease risk? That’s not clear.

The authors had a thought-provoking explanation for why the results were negative for heart disease, but positive for cancer. Remember that the participants in this trial started with a 25-hydroxyvitamin D level of 31 ng/ml and increased it to at least 42 ng/ml with vitamin D supplementation.

The authors stated that previous studies have suggested the 25-hydroxyvitamin D level associated with the lowest risk for heart disease is between 20 and 25 ng/ml. If that is true, most of the participants in this trial were already in the lowest possible risk for heart disease with respect to vitamin D status before the study even started. There would be no reason to expect additional vitamin D to further reduce their risk of heart disease.

In contrast, the authors said that previous studies suggest the 25-hydroxyvitamin D level associated with the lowest risk of cancer deaths is above 30 ng/ml. If that is true, it would explain why vitamin D supplementation in this study was effective at reducing cancer deaths.

However, previous placebo-controlled clinical studies have also been inconclusive with respect to vitamin D and heart disease. My recommendation would be to think of adequate vitamin D status as part of a holistic approach to reducing heart disease – one that includes a heart-healthy diet and a heart-healthy lifestyle – rather than a “magic bullet” that decreases heart disease risk by itself.

As for heart-healthy diets, I discuss the pros and cons of various diets in my book, “Slaying The Food Myths.”  As I discuss in my book, the weight of scientific evidence supports primarily plant-based diets that include omega-3s as heart healthy. As an example, the Mediterranean diet is primarily plant-based and is rich in healthy oils like olive oil and omega-3s. It is associated with reduced risk of both heart disease and cancer.

 

What Is The Truth About Vitamin D?

 

the truth about vitamin d signThere is a lot of confusion around the question of whether vitamin D reduces the risk of cancer. This study strengthened previous observation suggesting that vitamin D supplementation decreases cancer deaths. However, it is also consistent with previous studies that have failed to find an effect of vitamin D on cancer development. How can we understand this apparent discrepancy? The authors provided a logical explanation. They pointed out that:

  • Cancer development takes 20-30 years while this clinical study lasted only 5.3 years. That means that vitamin D supplementation only occurred at the tail end of the cancer development process. In fact, the cancer was already there in most of the patients in the study who developed cancer. It just had not been diagnosed yet. In the words of the authors: “Given the long latency for cancer development, extended follow-up is necessary to fully ascertain potential effects [of vitamin D supplementation].”
  • In contrast, none of the patients had been diagnosed with cancer when they entered the trial. That means that the patients were diagnosed with cancer during the 5.3-year study period. They were receiving extra vitamin D during the entire period of cancer treatment. Thus, the effect of vitamin D on reducing cancer deaths was easier to detect.

What Does This Study Mean For You?

the truth about vitamin d questionsVitamin D Is Likely To Decrease Your Risk Of Dying From Cancer: When you combine the results of this study with what we already know about vitamin D and cancer, the results are clear. Vitamin D appears to reduce your risk of dying from cancer. More importantly, the longer you have been supplementing with vitamin D, the greater your risk reduction is likely to be.

Vitamin D May Decrease Your Risk Of Developing Cancer: Association studies suggest that optimal vitamin D status is associated with decreased cancer risk, especially colon cancer risk. However, the long time for cancer development means that we may never be able to prove this effect through double-blind, placebo-controlled clinical trials.

Holistic Is Best: When you combine the VITAL study results with what we already know about vitamin D and heart disease, it appears that supplementing with vitamin D is unlikely to reduce your risk of developing heart disease unless you are vitamin D deficient. However, a holistic approach that starts with a healthy, primarily plant-based diet and makes sure your vitamin D status is adequate is likely to be effective.

The same is likely true for cancer. While the latest study suggests that vitamin D supplementation reduces your risk of dying from cancer, those vitamin D supplements are likely to be even more effective if you also adopt a healthy diet and lifestyle.

How Much Vitamin D Do You Need? The optimal dose of vitamin D is likely to be different for each of us. One of the things we have learned in recent years is that there are significant differences in the efficiency with which we convert vitamin D from diet and/or sun exposure into the active form of vitamin D in our cells. Fortunately, the blood test for 25-hydroxyvitamin D is readily available and is widely considered to be an excellent measure of our vitamin D status.

I recommend that you have your blood level of 25-hydroxyvitamin D tested on an annual basis. Based on the best currently available data, I recommend you aim for >20 ng/ml (50 nmol/L) if you wish to minimize your risk of heart disease and >30 ng/ml (75 nmol/L) if you wish to minimize your risk of cancer. If you can achieve those levels through diet and a multivitamin supplement, that is great. If not, I would recommend adding a vitamin D supplement until those levels are achieved.

Finally, you shouldn’t think of vitamin D as a magic bullet. If you are a couch potato and eat sodas and junk food, don’t expect vitamin D to protect you from cancer and heart disease. You should think of maintaining adequate 25-hydroxyvitamin D levels as just one component of a holistic approach to healthy, disease-free living.

 

The Bottom Line

 

There is a lot of confusion around the question of whether vitamin D reduces the risk of cancer and heart disease. A major clinical study has just been published that sheds light on these important questions. It reported:

  • Vitamin D did not decrease the risk of developing cancer during the 5.3-year study duration. The authors pointed out that cancer takes 20-30 years to develop, which means their study was probably too short to detect an effect of vitamin D on the risk of developing cancer.
  • Vitamin D did decrease the risk of dying from cancer, and the longer people were supplementing with vitamin D the bigger the protective effect of vitamin D was.
  • Vitamin D did not decrease the risk of heart disease. However, most study participants had a level of 25-hydroxyvitamin D that was optimal for reducing the risk of heart disease at the beginning of the study. There was no reason to expect that extra vitamin D would provide additional benefit.
  • With respect to both cancer and heart disease the best advice is to:
    • Get your 25-hydroxyvitamin D levels tested on an annual basis and supplement, if necessary, to keep your 25-hydroxyvitamin D levels in what the NIH considers to be an adequate range (20-50 ng/ml).
    • We do not have good dose response data for the beneficial effects of vitamin D on heart disease and cancer. However, according to this article, previous studies suggest you may want to am for 25-hydroxyvitamin D levels above 20 ng/ml to reduce the risk of heart disease and above 30 ng/ml to reduce your risk of cancer.
    • Consider vitamin D as just one component of a holistic approach to healthy, disease-free living.

For more details about the interpretation of these studies and what they mean for you, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

 

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